Parts of the Brain
Parts of the brain
1. The cerebrum or fore brain
2. Midbrain
3. Pons varolii
4. Medulla oblongata
5. Cerebellum or hindbrain
Coverings of the brain
Duramater
Arachnoid mater
piamater
Cerebrum
has the following lobes:-
frontal lobe anterior cranial fossa intelligence and memory
parietal lobe middle cranial fossa motor and sensory areas
temporal middle cranial fossa hearing speech areas
occipital posterior cranial fossa visual area
Midbrain
Is situated around the cerebral aqueduct between the cerebrum and the pons varolii
It has groups of nerve cells and nerve fibres which connect the cerebrum with the lower parts of the brain and spinal cord.
The cells are relay stations for ascending and descending nerve fibres.
Pons varolii
Situated in front of the cerebellum
Below the midbrain and above the medulla oblongata.
It consists of
- interconnecting fibres between the two hemispheres of the cerebellum
- fibres passing between the spinal cord and the higher levels of the brain
- nuclei of certain cranial nerves.
Pons Varolii
Situated in front of the cerebellum
Below the midbrain
Above the medulla oblongata
Consists of the
1. Fibres connecting the two hemispheres of the cerebellum
2. Fibres connecting the higher centres of the brain and the spinal cord 3. Nuclei of the 5th 6th 7th and 8th cranial nerves 4. Nuclei which act as relay stations
Cerebellum
An organ concerned with the coordination of the voluntary movements
It maintains posture and balance
Situation
Behind pons varolii
Below the posterior portion of cerebrum
In the posterior cranial fossa
Ovoid in shape
Two hemispheres
Seaparated by vermis a median strip of tissue
Grey matter forms the surface
White matter in depth
Cerebellum communicates with other regionof the CNS through three large nerve tracts called the cerebellar peduncles
The cerebellum consists of following three parts
Cerebellar activities are carried out below the level of consciousnes i.e. not under voluntary control
Sensory input for cerebellum
Derived from
Muscles and joints
Eyes
Ears (from semicircular canals)
Medulla oblongata
From pons varolii to the foramen magnum
Continues as the spinal cord below
Consists of
- relay stations for sensory nerves passing from the spinal cord to the cerebrum
- vital centres like cardiac centre
- respiratory centre
- vasomotor centre
- reflex centres of vomiting, coughing, sneezing and swallowing.
- decussation of the pyramids
- sensory decussation
